From: "J. Bruce Fields" <bfields@fieldses.org>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Al Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pavel Emelyanov <xemul@parallels.com>,
James Bottomley <jbottomley@parallels.com>,
Matthew Helsley <matt.helsley@gmail.com>
Subject: Re: [patch 4/8] fs, exportfs: Add export_encode_inode_fh helper
Date: Thu, 16 Aug 2012 08:47:03 -0400 [thread overview]
Message-ID: <20120816124703.GE28054@fieldses.org> (raw)
In-Reply-To: <20120816123814.GD1209@moon>
On Thu, Aug 16, 2012 at 04:38:14PM +0400, Cyrill Gorcunov wrote:
> On Thu, Aug 16, 2012 at 10:24:48AM +0400, Cyrill Gorcunov wrote:
> > > > > On the other hand, if you want a real filehandle then wouldn't you want
> > > > > to e.g. call the filesystem's ->encode_fh() if necessary, as
> > > > > exportfs_encode_fh() does?
> > > >
> > > > Well, one of the problem I hit when I've been trying to use encode_fh
> > > > is that every new implementation of encode_fh will require some size
> > > > (even unknown) in buffer where encoded data pushed. Correct me please
> > > > if I'm wrong. But with export_encode_inode_fh there is a small buffer
> > > > with pretty known size needed on stack needed for printing data in
> > > > fdinfo.
> > >
> > > You can just give encode_fh a too-small data and let it fail if it's not
> > > big enough.
> > >
> > > (In practice I think everyone supports NFSv3 filehandles which have a
> > > maximum size of 64 bytes.)
> >
> > I'll think about it, thanks!
>
> Hi Bruce, thinking a bit more I guess using general encode_fh is not that
> convenient since it operates with dentries while our fdinfo output deals
> with inodes. Thus I should either provide some new encode_fh variant
> which would deal with inodes directly without "parents".
I can't see why that wouldn't work.
> Which doesn't
> look for me anyhow better than the new export_encode_inode_fh helper.
That isn't going to work for filesystems that define their own
encode_fh:
$ git grep '\.encode_fh'
fs/btrfs/export.c: .encode_fh = btrfs_encode_fh,
fs/ceph/export.c: .encode_fh = ceph_encode_fh,
fs/fat/inode.c: .encode_fh = fat_encode_fh,
fs/fuse/inode.c: .encode_fh = fuse_encode_fh,
fs/gfs2/export.c: .encode_fh = gfs2_encode_fh,
fs/isofs/export.c: .encode_fh = isofs_export_encode_fh,
fs/nilfs2/namei.c: .encode_fh = nilfs_encode_fh,
fs/ocfs2/export.c: .encode_fh = ocfs2_encode_fh,
fs/reiserfs/super.c: .encode_fh = reiserfs_encode_fh,
fs/udf/namei.c: .encode_fh = udf_encode_fh,
fs/xfs/xfs_export.c: .encode_fh = xfs_fs_encode_fh,
mm/shmem.c: .encode_fh = shmem_encode_fh,
--b.
> After all, if the use of encode_fh become a mandatory rule we can easily
> extend fsnotify fdinfo output to support new scheme without breaking
> user space, because output looks like
>
> | fhandle-type: 1 f_handle: 49b1060023552153
>
> (ie if something is changed than these fields will be simply updated).
>
> Or maybe I miss something?
>
> Cyrill
next prev parent reply other threads:[~2012-08-16 12:47 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-15 9:21 [patch 0/8] procfs, fdinfo updated Cyrill Gorcunov
2012-08-15 9:21 ` [patch 1/8] procfs: Move /proc/pid/fd[info] handling code to fd.[ch] Cyrill Gorcunov
2012-08-15 9:21 ` [patch 2/8] procfs: Convert /proc/pid/fdinfo/ handling routines to seq-file Cyrill Gorcunov
2012-08-15 9:21 ` [patch 3/8] procfs: Add ability to plug in auxiliary fdinfo providers Cyrill Gorcunov
2012-08-15 21:16 ` Al Viro
2012-08-15 21:31 ` Cyrill Gorcunov
2012-08-15 21:29 ` Al Viro
2012-08-15 21:34 ` Cyrill Gorcunov
2012-08-16 10:58 ` Cyrill Gorcunov
2012-08-15 9:21 ` [patch 4/8] fs, exportfs: Add export_encode_inode_fh helper Cyrill Gorcunov
2012-08-15 20:45 ` J. Bruce Fields
2012-08-15 21:02 ` Cyrill Gorcunov
2012-08-15 22:06 ` J. Bruce Fields
2012-08-16 6:24 ` Cyrill Gorcunov
2012-08-16 12:38 ` Cyrill Gorcunov
2012-08-16 12:47 ` J. Bruce Fields [this message]
2012-08-16 13:16 ` Cyrill Gorcunov
2012-08-16 14:57 ` Cyrill Gorcunov
2012-08-16 15:05 ` Al Viro
2012-08-16 15:09 ` Cyrill Gorcunov
2012-08-16 13:43 ` Al Viro
2012-08-16 13:47 ` Pavel Emelyanov
2012-08-16 13:50 ` Al Viro
2012-08-16 13:53 ` Pavel Emelyanov
2012-08-16 13:54 ` Cyrill Gorcunov
2012-08-16 14:03 ` James Bottomley
2012-08-16 14:13 ` Pavel Emelyanov
2012-08-16 14:15 ` Cyrill Gorcunov
2012-08-16 14:41 ` Al Viro
2012-08-16 14:48 ` Cyrill Gorcunov
2012-08-16 14:54 ` J. Bruce Fields
2012-08-16 14:55 ` Al Viro
2012-08-16 15:06 ` Pavel Emelyanov
2012-08-16 15:35 ` Cyrill Gorcunov
2012-08-16 15:07 ` Cyrill Gorcunov
2012-08-17 20:58 ` Eric W. Biederman
2012-08-16 13:48 ` Al Viro
2012-08-20 14:19 ` Aneesh Kumar K.V
2012-08-20 16:33 ` Cyrill Gorcunov
2012-08-20 18:32 ` J. Bruce Fields
2012-08-20 19:06 ` Cyrill Gorcunov
2012-08-20 19:32 ` J. Bruce Fields
2012-08-20 19:40 ` Cyrill Gorcunov
2012-08-21 9:18 ` Pavel Emelyanov
2012-08-21 10:42 ` Aneesh Kumar K.V
2012-08-21 10:49 ` Pavel Emelyanov
2012-08-21 10:54 ` Cyrill Gorcunov
2012-08-21 11:09 ` Pavel Emelyanov
2012-08-21 12:11 ` J. Bruce Fields
2012-08-21 12:22 ` Pavel Emelyanov
2012-08-21 12:29 ` J. Bruce Fields
2012-08-21 12:40 ` Pavel Emelyanov
2012-08-21 12:51 ` Boaz Harrosh
2012-08-21 12:59 ` Pavel Emelyanov
2012-08-21 13:08 ` Boaz Harrosh
2012-08-21 13:12 ` Al Viro
2012-08-21 13:40 ` Cyrill Gorcunov
2012-08-21 12:09 ` J. Bruce Fields
2012-08-21 12:25 ` Pavel Emelyanov
2012-08-22 5:49 ` Aneesh Kumar K.V
2012-08-23 8:06 ` Cyrill Gorcunov
2012-08-23 8:54 ` Marco Stornelli
2012-08-23 9:29 ` Cyrill Gorcunov
2012-08-15 9:21 ` [patch 5/8] fs, notify: Add procfs fdinfo helper v3 Cyrill Gorcunov
2012-08-15 9:21 ` [patch 6/8] fs, eventfd: Add procfs fdinfo helper Cyrill Gorcunov
2012-08-15 9:21 ` [patch 7/8] fs, epoll: Add procfs fdinfo helper v2 Cyrill Gorcunov
2012-08-15 9:21 ` [patch 8/8] fdinfo: Show sigmask for signalfd fd v2 Cyrill Gorcunov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120816124703.GE28054@fieldses.org \
--to=bfields@fieldses.org \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=gorcunov@openvz.org \
--cc=jbottomley@parallels.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=matt.helsley@gmail.com \
--cc=viro@zeniv.linux.org.uk \
--cc=xemul@parallels.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).